Method of dry etching copper thin film and semiconductor device

ABSTRACT

A method of etching a copper (Cu) thin film and a Cu thin film prepared therefrom, the method including patterning a hard mask layer on the Cu thin film to form a hard mask on the Cu thin film; forming a plasma of a mixed gas, the mixed gas including an inert gas and an organic chelator material including an amine group, the mixed gas not including a halogen gas or a halide gas; and etching the Cu thin film through the hard mask using the plasma generated in the forming of the plasma of the mixed gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application based on pending application Ser. No.16/728,342, filed Dec. 27, 2019, the entire contents of which is herebyincorporated by reference.

Korean Patent Application No. 10-2018-0172134, filed on Dec. 28, 2018,in the Korean Intellectual Property Office, and entitled: “Method of DryEtching Copper Thin Film,” is incorporated by reference herein in itsentirety.

BACKGROUND 1. Field

Embodiments relate to a method of dry etching a copper thin film.

2. Description of the Related Art

Copper (Cu) is widely used as an electrode material in various devices.In semiconductor devices, Cu may be used only in some devices, andaluminum (Al) may be more widely used. As a fine line width of a deviceis reduced to several nanometers (nm), a density of a current that flowsthrough an Al wiring line may increase. For example, in a metal wiringline manufactured using Al, due to an electron-movement characteristicthat deteriorates at high current density, the reliability of a devicecould deteriorate. An Al electrode and an Al wiring line may not bedesirable, and it may be desirable to use a Cu wiring line in place ofthe Al electrode and the Al wiring line.

Cu has a lower specific resistance value than Al, and a semiconductordevice, in which Cu is used may have a higher information processingspeed than a semiconductor device, in which Al is used, (Al: 2.7μΩ·cmand Cu: 1.7μΩ·cm). In addition, Cu has a greater number of atoms and ahigher melting point than Al, and the resistance against electrontransfer is high at high current density.

SUMMARY

The embodiments may be realized by providing a method of etching acopper (Cu) thin film, the method including patterning a hard mask layeron the Cu thin film to form a hard mask on the Cu thin film; forming aplasma of a mixed gas, the mixed gas including an inert gas and anorganic chelator material including an amine group, the mixed gas notincluding a halogen gas or a halide gas; and etching the Cu thin filmthrough the hard mask using the plasma generated in the forming of theplasma of the mixed gas.

The embodiments may be realized by providing a method of etching acopper (Cu) thin film, the method including patterning a hard mask layeron the Cu thin film to form a hard mask on the Cu thin film; forming aplasma of a mixed gas, the mixed gas including piperidine, an alcohol,and inert gas and not including a halogen gas or a halide gas; andetching the Cu thin film through the hard mask using plasma generated bythe forming of the plasma of the mixed gas.

The embodiments may be realized by providing a method of etching acopper (Cu) thin film, the method including providing the Cu thin filmon a substrate; forming a hard mask layer in the Cu thin film; etchingthe hard mask layer to form a hard mask on the Cu thin film; and plasmaetching the Cu thin film through the hard mask using plasma generatedfrom a mixed gas including an inert gas and an organic chelator materialincluding an amine group.

The embodiments may be realized by providing a copper (Cu) thin filmmanufactured by the method according to an embodiment, the Cu thin filmhaving a sidewall slope of 70° or greater.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will be apparent to those of skill in the art by describing indetail exemplary embodiments with reference to the attached drawings inwhich:

FIG. 1A illustrates a thin film structure before performing etching;

FIG. 1B illustrates a thin film structure after etching a hard mask andbefore etching a copper (Cu) thin film;

FIG. 1C illustrates a structure of a thin film etched by an ion millingetching method;

FIGS. 1D and 1E illustrate structures of thin films etched by a reactiveion etching method;

FIG. 2 illustrates a reactive experiment image of a Cu thin film, inwhich piperidine was used;

FIG. 3 illustrates a graph showing etching properties of a Cu thin filmand an SiO₂ hard mask that were etched by using a piperidine/Ar gas by ahigh density plasma reactive ion etching method by changing the amountof piperidine and etch selectivity of the Cu thin film for the hardmask;

FIG. 4 illustrates etching profiles of a 1 μm line pattern etched usinga piperidine/Ar gas by a high density plasma reactive ion etching methodby changing the amount of piperidine for a SiO₂/Cu thin film;

FIG. 5 illustrates etching profiles of a 0.5 μm (500 nm) line patternetched using a piperidine/Ar gas by a high density plasma reactive ionetching method by changing the amount of piperidine for a SiO₂/Cu thinfilm;

FIG. 6 illustrates a graph showing etching properties of a Cu thin filmand an SiO₂ hard mask that are etched by using a C₂H₅OH/piperidine/Argas by a high density plasma reactive ion etching method by changing theconcentration of C₂H₅OH and etch selectivity of the Cu thin film for thehard mask; and

FIG. 7 illustrates etching profiles of a 0.5 μm (500 nm) line patternetched using a C₂H₅OH/piperidine/Ar gas by a high density plasmareactive ion etching method by changing the amount of C₂H₅OH for aSiO₂/Cu thin film.

DETAILED DESCRIPTION

A method of etching a copper (Cu) thin film, according to an embodiment,may include patterning a hard mask layer on the Cu thin film to form ahard mask on the Cu thin film, forming a plasma of a mixed gas, andetching the masked Cu thin film using plasma generated in the forming ofthe plasma of the mixed gas. The mixed gas may include an inert gas andat least one organic chelator material including amine groups. The mixedgas may not include either a halogen gas or a halide gas (e.g., may notinclude a halogen-containing gas or a halide-containing gas).

The patterning of the hard mask (and the masking of the Cu thin film)may include patterning a photoresist mask on the hard mask layer/Cu thinfilm, etching the hard mask layer using the photoresist mask to form ahard mask, and removing the photoresist mask, e.g., patterning the hardmask by using the photoresist mask.

In an implementation, the hard mask may include, e.g., a ceramic such asSiO₂ or Si₃N₄, a metal such as titanium (Ti), titanium nitride (TiN),tantalum (Ta), or tungsten (W), or amorphous carbon. In animplementation, a material with high etch selectivity, which is etchableby an etching gas at a low etching rate, may be used as the hard mask.In an implementation, SiO₂ may be used as the hard mask. As used herein,the term “or” is not an exclusive term, e.g., “A or B” would include A,B, or A and B.

In an implementation, the etch selectivity means an etching rate of theCu thin film with respect to an etching rate of the hard mask, which maybe calculated according to the following equation.

etch selectivity=(the etching rate of the Cu thin film)/(the etchingrate of the hard mask)

In an implementation, in the etching processes, the photoresist mask maybe patterned to mask the SiO₂ hard mask layer and the Cu thin film.Then, using the photoresist mask, the SiO₂ hard mask layer may be etchedwith a plasma generated from a C₂F₆/Cl₂/Ar gas. After etching the SiO₂hard mask layer, the photoresist mask may be removed by using plasma ofan oxygen gas and accordingly, the Cu thin film may be masked by thehard mask (e.g., the patterned SiO₂ thin film).

In the forming of a plasma of the mixed gas, the organic chelatormaterial including the NH group (amine group) may include, e.g.,piperidine, piperazine, triazacyclononane (TACN),1,4,7,10-tetraazacyclododecane (Cyclen), or1,4,8,11-tetraazacyclotetradecane (Cyclam).

In an implementation, in the forming of a plasma of the mixed gas, theinert gas may include, e.g., helium (He), neon (Ne), argon (Ar), or N₂.

In an implementation, the Cu thin film may be etched by the plasma ofthe mixed gas of, e.g., the organic chelator material including the NHgroup (amine) and Ar. In an implementation, the concentration or amountof the organic chelator material (including the NH group) in the mixedgas may be, e.g., 25 vol % to 75 vol %, and a remaining portion of themixed gas may be the inert gas of, e.g., Ar, in balance.

If pure Ar gas were to be used, physical etching may be performed by Arions, and a large amount of re-deposition could occur around the etchedCu thin film. Maintaining the amount of the organic chelator material at25 vol % or greater may help prevent a large amount of material frombeing re-deposited on side walls of the Cu thin film. Maintaining theamount of the organic chelator material (including the NH group) at 75vol % or less may help ensure that, although the Cu thin film is etched,a small amount of material is not deposited on the SiO₂ hard mask. Ifthe amount of the organic chelator material were 100 vol %, the Cu thinfilm would not be etched.

When etching is performed by increasing the concentration of the organicchelator material from 25 vol % to 75 vol %, the amount of materialre-deposited on the side walls of the Cu thin film may be graduallyreduced and an increased sidewall slope may be obtained. When theconcentration of the organic chelator material is 75 vol %,re-deposition may not occur, and the sidewall slope of about 70 degreesmay be obtained.

In the forming of the plasma of the mixed gas, the mixed gas may be madeinto plasma by, e.g., an inductively coupled plasma reactive ion etchingmethod, a high density plasma reactive ion etching method, a magneticenhanced reactive ion etching method, a reactive ion etching method, anatomic layer etching method, or a pulse modulated high density plasmareactive ion etching method.

In the etching of the Cu thin film using the generated plasma, atemperature of a substrate may be 10° C. to 20° C. During the etching ofthe Cu thin film, it is not necessary to heat the substrate on which theCu thin film is loaded and a cooling fluid of 10° C. to 20° C. may beapplied to the substrate to etch the Cu thin film at a low temperature.If the substrate were to be heated to 150° C. or higher, a vacuum sealsuch as an O-ring may not be used under the substrate and accordingly, aspecial substrate structure may be required and cost of an apparatusincreases. In addition, if the substrate were to be heated to a hightemperature of 150° C. for a significant time, materials that werepreviously deposited on the substrate or patterned/etched could diffusedand accordingly, undesired materials (e.g., atoms) may migrate upward ordownward the Cu thin film layer and change or deteriorate acharacteristic of a device.

In an implementation, in the method of etching the Cu thin film,according to the embodiments, etch selectivity of the Cu thin film withrespect to the hard mask may be, e.g., about 3 to about 5.

In the method of etching the Cu thin film, according to the embodiments,an optimal etching gas with optimal concentration and an optimal etchingprocess condition may applied to help reduce or prevent re-deposition,in comparison with other methods of etching the Cu thin film, and toprovide a high etching rate and a high anisotropic etching profilewithout forming an etching residue. For example, the method of etchingthe Cu thin film, according to the embodiments, may be applied to alldevices and apparatuses in which the Cu thin film is used.

<Manufacturing Example: Patterning of Hard Mask>

The SiO₂ hard mask may be formed by patterning a photoresist by alithography process and etching the SiO₂ thin film with a C₂F₆/Ar gas.The SiO₂ thin film etched at a concentration of C₂F₆ of 25%˜30% may havea perpendicular sidewall slope of no less than 85 degrees.

FIG. 1A illustrates a specimen structure before etching the hard maskand the Cu thin film. FIG. 1B illustrates a hard mask (e.g., SiO₂)/Cuspecimen in which the hard mask has been dry etched with the C₂F₆/Ar gasand has a perpendicular sidewall slope of no less than 85 degrees. FIG.1C illustrates a result of etching the Cu thin film by using thepatterned hard mask in which a large amount of re-deposition materialsare formed on side surfaces of the Cu thin film, which is mainly etchedby a physical sputtering etching mechanism. In FIG. 1D, after performingthe etching, no re-deposition materials may be formed on the etched sidesurfaces. The sidewall of the etched Cu thin film may be excessivelyslanted, and a Cu fine pattern of a desired size may not be formed. FIG.1E illustrates a perpendicular anisotropic etching profile obtained byusing a proper etching gas under optimal etching reaction conditionswhen the Cu thin film is etched.

FIG. 2 illustrates an experiment in which a piperidine chelator compound(including one NH group) was used, solutions were respectively heated to60° C., 90° C., 120° C., and 150° C., and the specimen was reacted withthe heated solutions or vapors from the heated solutions. For example,after putting certain amounts of piperidine solutions into beakers andchanging temperatures of the solutions to 60° C., 90° C., 120° C., and150° C., reaction speeds between the solutions and gases generated fromthe solutions were measured.

Table 1, below, illustrates reactivity of the Cu thin film measured byhaving the Cu thin film react with the heated solutions and the vaporsgenerated therefrom for ten minutes.

Piperidine is liquid at ambient temperature and has a boiling point of106° C. When the temperature of the solution was 60° C., the Cu thinfilm was not etched in the solution. When the temperature of thesolution is 90° C., the Cu thin film started to be etched. Vaporsgenerated from the piperidine solutions of 60° C. and 90° C. did notreact with Cu. However, vapors generated from the piperidine solutionsof 120° C. and 150° C. reacted with Cu. Reactivity of the solutions andvapors to Cu increased as temperatures of the solutions increase andaccordingly, higher etching rates were obtained.

TABLE 1 Solution Cu reaction rate Cu reaction rate temperature inpiperidine in piperidine (° C.) liquid (Å/min) vapor (Å/min) 60 0 0 9062 0 120 94.7 52 150 129.2 88.4

<Measured Reaction Rates Between the Piperidine Solutions Obtained fromthe Experiment Conditions of FIG. 2 and the Cu Thin Film>

Table 2, below, summarizes a result of an experiment in which apiperazine chelator compound including two NH groups was used.Piperazine is solid at ambient temperature and has a melting point of106° C. and a boiling point of 146° C. In order to make piperazineliquid at ambient temperature, piperazine was dissolved in ethyleneglycol (EG) as a solvent. 400 mg of piperazine was dissolved in 40 ml ofethylene glycol and was heated to 100° C., 130° C., 160° C., and 190° C.The specimen was reacted with the piperazine solution and vaporsgenerated therefrom for ten minutes, and an etching rate of Cu wasmeasured.

In order to investigate whether the solvent, ethylene glycol, reactswith Cu, the same experiment was performed by using only the solvent. Inthe solvent, ethylene glycol, the reaction rate of Cu was very high andsignificantly increased with temperature from 26 Å/min at 100° C. to 92Å/min at 190° C. Furthermore, the reaction rate of Cu in the solutionobtained by dissolving piperazine in the solvent, i.e., ethylene glycol,was not significantly different from that of Cu in the solvent andslightly increased, e.g., from 27 Å/min at 100° C. to 98 Å/min at 190°C.,

This shows that the solvent, ethylene glycol, reacts with Cu. In theexperiment illustrating reactivity of vapors of the solutions with Cu,at 100° C., Cu did not react with vapors of the mixed solutions, at 130°C., a reaction rate of 9 Å/min was obtained, and, at 190° C., a reactionrate of 31 Å/min was obtained.

TABLE 2 Cu etch Cu etch Cu etch rate in EG + Cu etch rate in EG +solution rate in EG piperazine rate in piperazine temperature solventsolution EG vapor vapor (° C.) (Å/min) (Å/min) (Å/min) (Å/min) 100 26 270 0 130 44 48 8 9 160 65 67 19 23 190 92 98 27 31

<Experiment Result with Respect to the Cu Thin Film Using Piperazine>

Table 3, below, summarizes a result of an experiment in which a1,4,7-triazacyclononane (TACN) chelator compound including three NHgroups was used. TACN is solid at an ambient temperature and has amelting point of 42° C. to 45° C. and a boiling point of 254° C. Inorder to make TACN liquid, a solution thereof was prepared. TACN wasdissolved by mainly using ethylene glycol and was vaporized. To thisend, the solutions were heated from 150° C. to 270° C. at intervals of20° C. to generate vapors of the solutions.

An etching rate of the Cu thin film in the vapor generated from thesolution of 150° C. was 34.7 Å/min, an etching rate of the Cu thin filmin the vapor generated from the solution of 190° C. was 63 Å/min, and anetching rate of the Cu thin film in the vapor generated from thesolution of 270° C. was 118.5 Å/min, which was the highest etching rate.

TABLE 3 Cu etch rate in Cu etch rate in temperature EG vapor EG + TACN(° C.) (Å/min) vapor (Å/min) 150 12.4 34.7 170 21 48.2 190 27 63 21037.6 79.5 230 45.1 91 250 52.3 101.7 270 63.5 118.5

<Experiment Result with Respect to the Cu Thin Film Using1,4,7-Triazacyclononane (TACN)>

In TABLE 4, below, the reactive etching rates with regard to thepiperidine, ethylene glycol (EG), piperazine/EG, and TACN/EG solutionsof Tables 1 to 3 and the Cu thin film are consolidated into one tableand compared.

The temperatures of the solutions were different from each other, and itis difficult to directly compare the etching rates with each other.However, when the etching rates are compared with each other at the sametemperature, the etching rate of the Cu thin film with respect to thepiperidine solution was 88.4 Å/min at 150° C., which is highest, theetching rate of the Cu thin film with respect to the EG/TACN solutionwas 34.7 Å/min, and the etching rate of the Cu thin with respect to theEG/piperazine film solution was 23 Å/min at 160° C., which is lowest.

TABLE 4 Cu reaction Cu etch rate rate in Cu etch in EG + Cu etch rateTemp- piperidine rate in piperazine in EG + erature vapor EG vapor vaporTACN vapor (° C.) (Å/min) (Å/min) (Å/min) (Å/min) 90 0 100 0 0 − 120 52130 8 9 150 88.4 12.4 34.7 160 19 23 170 21 48.2 190 27 31 63 210 37.679.5 230 45.1 91 250 52.3 101.7 270 63.5 118.5

<Reactive Etching Rates Between Piperidine, Ethylene Glycol (EG),Piperazine/EG, and TACN/EG Solutions and the Cu Thin Film at RespectiveTemperatures >

FIG. 3 illustrates a graph showing etching properties of a Cu thin filmby an inductively coupled plasma reactive ion etching method whilechanging the amount of piperidine to 0 vol %, 25 vol %, 50 vol %, 75 vol%, and 100 vol % in the mixed gas of piperidine/Ar. As the concentrationof piperidine increased, etching rates of the Cu thin film and the hardmask gradually decreased. When the amount of pieridine in the mixed gaswas 75 vol %, the Cu thin film was etched and a small amount ofdeposition material was formed on the SiO₂ hard mask. When piperidinewas used in an amount of 100 vol %, the Cu thin film was not etched.

FIG. 4 illustrates etching profiles of 1 μm line patterned SiO₂/Cuetched by an inductively coupled plasma reactive ion etching methodwhile changing the amount of piperidine to 0 vol %, 25 vol %, 50 vol %,75 vol %, and 100 vol=% in the mixed gas of piperidine/Ar. The etchingprofiles of SiO₂/Cu etched by (a) pure Ar, (b) 25 vol % piperidine, (c)50 vol % piperidine, and (d) 75 vol % piperidine are illustrated. Whenthe pure Ar gas was used, physical etching was performed by Ar ions, anda large amount of re-deposition occurred around the etched Cu thin film.When etching was performed by increasing piperidine from 25 vol % to 75vol %, a re-deposition material gradually reduced on side walls of theCu thin film and re-deposition did not occur when 75 vol % of piperidinewas used. Sidewall slopes were 75, 72, and 70 degrees with respect toamounts of piperidine of 25 vol %, 50 vol %, and 75 vol %.

FIG. 5 illustrates etching profiles of 0.5 μm (500 nm) line patternedSiO₂/Cu etched under the same condition of FIG. 4. As in the resultobtained by the 1 μm pattern, when etching was performed by increasingpiperidine from 25 vol % to 75 vol %, the re-deposition material wasgradually reduced on the side walls of the Cu thin film, and, when 100vol % of piperidine was used, the Cu thin film was not etched and apolymer film was deposited. The etching profiles of SiO₂/Cu etched by(a) 25 vol % piperidine, (b) 50 vol % piperidine, (c) 75 vol %piperidine, and (d) 100 vol % of piperidine are illustrated.

According to another embodiment, a method of etching a Cu thin film mayinclude patterning a hard mask to mask the Cu thin film, forming aplasma of a mixed gas including piperidine, alcohol (R—OH), and inertgas, and etching the masked Cu thin film using plasma formed in theforming of the plasma of the mixed gas.

In the mixed gas, the concentration or amount of piperidine may be fromabout 5 vol % to about 20 vol %, etch selectivity of the Cu thin filmwith respect to the hard mask may be about 1 to about 3, and a sidewallslope may be about 70 degrees or more.

In an implementation, like in a case in which alcohol is not included inthe mixed gas, the inert gas in the forming of the plasma of the mixedgas may include He, Ne, Ar, or N₂, and a temperature of a substrate maybe about 10° C. to about 20° C. in the etching of the Cu thin film.Furthermore, a sidewall slope may be about 70 degrees or more.

FIG. 6 illustrates a graph showing etching properties of the Cu thinfilm by the inductively coupled plasma reactive ion etching method withadding C₂H₅OH to a first mixed gas of 60 vol % of piperidine/Ar, whilechanging the amount of C₂H₅OH to 0 vol %, 5 vol %, 10 vol %, 15 vol %,and 20 vol % in a second mixed gas of C₂H₅OH/piperidine/Ar. As theconcentration of C₂H₅OH increased, the etching rate of the Cu thin filmwas gradually reduced and etching rates of the SiO₂ hard mask did notsignificantly change. For example, etch selectivity of Cu with respectto the hard mask was gradually reduced.

FIG. 7 illustrates etching profiles of SiO₂/Cu etched by the inductivelycoupled plasma reactive ion etching method with adding C₂H₅OH to a firstmixed gas of 60 vol % piperidine/Ar (i.e., piperidine 60 vol %) whilechanging the amount of C₂H₅OH to 0 vol %, 5 vol %, 10 vol %, 15 vol %,and 20 vol % in a second mixed gas of C₂H₅OH/piperidine/Ar. As theconcentration of C₂H₅OH increased, re-deposition after etching wassignificantly reduced. When the amount of C₂H₅OH was 5 vol %,re-deposition was not observed. When the amount of C₂H₅OH was 20 vol %,the sidewall slope of Cu is significantly increased to about 75 degreesor more. Etching profiles of SiO₂/Cu etched by (a) the first mixed gas(i.e., 60 vol % of piperidine/Ar), (b) C₂H₅OH of 5 vol % in the secondmixed gas, (c) C₂H₅OH of 10 vol % in the second mixed gas, (d) C₂H₅OH of15 vol % in the second mixed gas, and (e) C₂H₅OH of 20 vol % in thesecond mixed gas are illustrated.

By way of summation and review, it may be difficult to create a compoundby using Cu, and dry etching may not be implemented and a specialprocess referred to as a damascene process may be used. The resistanceof an electrode may increase when a fine line width of a metal electrodeor a metal wiring line is reduced to several nanometers (nm) even in thedamascene process, and a dry etching process of Cu may be considered.

In some damascene processes, after forming a diffusion barrier on asemiconductor substrate including a trench, a Cu wiring line may beformed by depositing a Cu layer and performing chemical mechanicalpolishing (CMP) process. After patterning a hard mask on a Cu layer andmasking the patterned hard mask, the Cu layer may be dry etched by usingan etching system including Cl atoms and accordingly, a Cu metal wiringline may be manufactured.

A wet etching method or a dry etching method may be used for a processof etching thin films for performing fine patterning. As a size ofpatterns to be etched is reduced to no more than several micrometers, itmay be difficult to apply the wet etching method. For example, the dryetching method, in which plasma faithful to transmitting the patterns isused, may be desirable.

The dry etching method, in which low pressure plasma is used, may beclassified into an ion milling etching method and a reactive ion etchingmethod by chemical reactivity of plasma. In the ion milling etchingmethod, etching is performed by using argon (Ar) plasma that is an inertgas. In the reactive ion etching method, etching is performed by usingvarious chemical gases.

Cl-based gases such as SiCl₄, CCl₄, Cl₂, and HCl may be used and anetching gas such as HBr may be applied. An etching rate of Cu may bevery low, and hard masks such as a metal or an oxide layer may be used.When the Cl-based gases are used as the etching gases, an etchingproduct of CuCl_(x) may be generated. For example, rather than etchingthe Cu thin film, a layer of CuCl_(x) may be grown on the Cu thin filmand the Cu thin film may thicken, which may be observed by a scanningelectron microscope (SEM). Such CuCl_(x) compounds may be removed by anHCl solution or H₂ plasma processing. A final etched pattern of Cu maynot be excellent and etching of a fine pattern may not be achieved.

By using hexafluoroacetylacetonate (hfac) that is a kind of an organicchelator material and heating a substrate to 90° C. to 160° C., anorganic metal compound including hfac having low melting and boilingpoints and high volatility may be formed and accordingly, a Cu etchingreaction may be easily performed. A fine pattern may not be successfullyformed. Dry etching on a Cu thin film could be performed using ahydrogen gas at a low temperature, e.g., etching may be performed on theCu thin film by using hydrogen and a mixed gas of hydrogen/argon underetching conditions.

When a Cu thin film is etched, in a case in which ion milling, in whichan apparatus is simple and a physical etching mechanism is used, is usedor a size of a pattern is no more than about 5 μm to about 10 μm, asillustrated in FIG. 1B, re-deposition could occur around the etchedpattern and accordingly, a fence may be formed, which may be caused bythe etching mechanism of the ion milling etching method, in which a partof a thin film material is sputtering and removed only by collisionenergy of Ar positive ions without a chemical reaction.

The dry etching process for the Cu thin film may be performed using newetching gases and optimal etching processes. For example, when the Cuthin film is etched in order to manufacture highly integrated devices,the reactive ion etching method, to which chemical reaction is applied,may be used. In addition, a high density plasma reactive ion etchingmethod, in which plasma density is high and accordingly, an etching rateis high and etch selectivity may increase, may be used. For example, Cuhas extremely small or no reactivity, an etching rate may be very low,and accordingly, etch selectivity of the Cu thin film with respect to anetching mask may be very small. For example, when photoresist is used asa mask in a lithography process, a Cu pattern etched under an etchingcondition may not be formed. For example, instead of photoresist,etching may be performed by using a thin film formed of a metal such asTi, Ta, W, TiN, or Cr or a metal oxide such as TiO₂ or SiO₂, e.g., ahard mask.

The Cu thin film may be etched by the reactive ion etching method, andif an improper etching gas or an etching gas with improper density wereto be used or an improper etching process were to be used, re-depositioncould occur on side surfaces of the etched pattern. In addition, ifetching were to be performed by using an etching gas that is notoptimized or under an etching condition that is not optimized, theoccurrence of re-deposition may be reduced. However, as illustrated inFIG. 1C, a slope of an etched side surface (a sidewall slope) could bevery steep, and may not be applied to the etching of the fine pattern.

A Cu thin film etching technology according to an embodiment may becapable of providing a high etching rate and a high anisotropic etchingprofile by using a proper etching gas and controlling the density of theetching gas.

One or more embodiments may provide a method of etching a Cu thin film,in which an optimal etching process condition is applied to the Cu thinfilm by using an organic chelator material including an NH group.

One or more embodiments may provide a pattern formed by performingetching by using a dry etching method without patterning a copper (Cu)thin film used as a semiconductor material such as an electrode or awiring line by a damascene process.

One or more embodiments may provide a method of etching a Cu thin filmcapable of preventing re-deposition from occurring and providing a highetching rate and an etching profile of high anisotropy without anetching residue by using an etching gas.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

What is claimed is:
 1. A method of etching a copper (Cu) thin film, themethod comprising: patterning a hard mask layer on the Cu thin film toform a hard mask on the Cu thin film; and etching the Cu thin filmthrough the hard mask using a plasma of a mixed gas; wherein the Cu thinfilm has a sidewall slope of 70° or greater after the etching.
 2. Themethod of as claimed in claim 1, wherein the mixed gas includes an inertgas and an organic chelator material including an amine group, the mixedgas not including a halogen gas or a halide gas.
 3. The method asclaimed in claim 2, wherein the organic chelator material includespiperidine, piperazine, 1,4,7-triazacyclononane,1,4,7,10-tetraazacyclododecane, or 1,4,8,11-tetraazacyclotetradecane. 4.The method as claimed in claim 2, wherein the mixed gas includes theorganic chelator material in an amount of 25 vol % to 75 vol %, based ona total volume of the mixed gas.
 5. The method as claimed in claim 4,wherein the organic chelator material includes piperidine.
 6. The methodas claimed in claim 2, wherein the inert gas includes helium, neon,argon, or N₂.
 7. The method as claimed in claim 1, wherein an etchselectivity of the Cu thin film with respect to the hard mask is about 3to about
 5. 8. The method as claimed in claim 1, wherein the hard maskincludes SiO₂, Si₃N₄, titanium, titanium nitride, tantalum, tungsten, oramorphous carbon.
 9. The method as claimed in claim 1, wherein: the Cuthin film is on a substrate, and in the etching of the Cu thin film, atemperature of the substrate is 10° C. to 20° C.
 10. A method of etchinga copper (Cu) thin film, the method comprising: providing the Cu thinfilm on a substrate; forming a hard mask layer on the Cu thin film;etching the hard mask layer to form a hard mask on the Cu thin film; andplasma etching the Cu thin film through the hard mask using plasmagenerated from a mixed gas including an inert gas and an organicchelator material including an amine group, wherein the Cu thin film hasa sidewall slope of 70° or greater after the plasma etching.
 11. Themethod as claimed in claim 10, wherein the mixed gas further includes analcohol in an amount of 5 vol % to 20 vol %, based on a total volume ofthe mixed gas.
 12. The method as claimed in claim 10, wherein theorganic chelator material includes piperidine, piperazine,1,4,7-triazacyclononane, 1,4,7,10-tetraazacyclododecane, or1,4,8,11-tetraazacyclotetradecane.
 13. The method as claimed in claim10, wherein the mixed gas includes the organic chelator material in anamount of 25 vol % to 75 vol %.
 14. The method as claimed in claim 13,wherein the organic chelator material includes piperidine.
 15. Themethod as claimed in claim 10, wherein the mixed gas does not include ahalogen-containing gas or a halide-containing gas.
 16. The method asclaimed in claim 10, wherein the hard mask includes SiO₂, Si₃N₄,titanium, titanium nitride, tantalum, tungsten, or amorphous carbon. 17.The method as claimed in claim 10, wherein the inert gas includeshelium, neon, argon, or N₂.
 18. The method as claimed in claim 10,wherein in the plasma etching of the Cu thin film, a temperature of thesubstrate is 10° C. to 20° C.
 19. A semiconductor device, thesemiconductor device comprising: a substrate; a Cu pattern on thesubstrate; a hard mask on the Cu pattern, the hard mask being alignedwith the Cu pattern; and the Cu pattern having a sidewall slope of 70°or greater.
 20. The semiconductor device as claimed in claim 19, whereinthe hard mask includes SiO₂, Si₃N₄, titanium, titanium nitride,tantalum, tungsten, or amorphous carbon.